共查询到20条相似文献,搜索用时 109 毫秒
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采用过冷熔体定向约束生长法生长了尺寸约为30 mm×14 mm×7 mm的块状4-氨基二苯甲酮晶体,并对生长晶体的光学均匀性、光学透过率、二次谐波转换效率以及激光损伤阈值等性能进行了测试.结果表明:定向生长的4-氨基二苯甲酮晶体在650~1200 nm波段内具有90;以上的光学透过率;最高二次谐波转换效率达到64.9;;单点激光脉冲损伤阈值分别为205.4 GW/cm2(输入光波为1064 nm)和267.2 GW/cm2(输入光波为532 nm).采用过冷熔体定向约束生长的4-氨基二苯甲酮晶体适合于用作Nd: YAG激光的二次倍频器件,也适合于用作650~1200 nm波段的光学调制器件. 相似文献
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本文对采用双坩埚提拉法(DCCZ)生长的化学计量比LiNbO3晶体中出现的机械双晶、组分过冷、包裹体等宏观生长缺陷进行了观察和分析.结果表明机械双晶通常以{102}和{104}面族为双晶面,而不是以前文献报道的{102}和{012}面族;化学计量比LiNbO3晶体双坩埚提拉法生长与同成份晶体生长不同,前者是助熔剂生长体系,生长速度稍快或温度较小的波动就会导致组分过冷,而后者属于纯熔体生长体系,不容易产生组分过冷;包裹体是由于组分过冷生长时界面失稳夹入熔体所造成的.由于这些缺陷的存在都会严重影响单晶的获得率和质量,为此,我们通过大量实验研究后提出了可以减少和避免这些生长缺陷提高晶体质量的方法. 相似文献
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The morphological variety of crystal habits is due to differences in relative growth rates of faces of which the crystal is composed. For equilibrium, the growth rates of faces are proportional to the distances from the centre of the crystal to the respective hkl faces. According to the BFDH law, such distances are inversely proportional to the interplanar distances, therefore the observed crystal faces are those with the largest interplanar distances. This paper tries to explain some peculiarities of the crystal morphology deduced from the BFDH law and shows that the crystal geometry influences morphological importance of faces and because of crystal geometry, the faces of the largest interplanar distances are not necessarily the largest faces in the BFDH morphology. 相似文献
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Wang Buguo Zhong Weizhuo Ye Cheng Shi Erwei Yin Zhiwen 《Journal of Crystal Growth》1996,160(3-4):375-381
The growth habits of the polar organic crystal N-4-nitrophenyl-(L)-prolinol (NPP) in organic solvents have been studied from the standpoint of the incorporation of growth units. Qualitative explanations of the observed growth forms are based on (1) the interaction between the solvent molecules and the growth units, and (2) the influence of the solvent molecules on growth interfaces, particularly on two polar faces of the polar organic crystal. Since the incorporation rates of the growth units are different on positive and negative polar faces, a variety of growth habits appear. The surface structures of the grown crystal have been investigated through ex-situ observations of atomic force microscopy (AFM). 相似文献
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β-BaB2O4 (BBO) crystals with well-defined morphology have been grown from Na2O solutions using the top seeded solution growth (TSSG) method. The crystal morphology in relation to its structure and growth conditions has been studied in detail on the basis of crystallography and crystal chemistry. It is found that the morphological characteristics are related to the orientations of structural unit (B3O6)3— anion rings in the crystal. On the other hand, the growth parameters may greatly affect the appearance of faces of the crystal, but the crystals still generally take trigonal in outline and have a diagnostic character of point group 3m. The observed morphology is in disagreement with BFDH and PBC analyses and is explained from the incorporation of the growth units on the faces and facets. Since the incorporation rates of the growth units are different on different faces, the boule habits with well-defined morphology are formed. 相似文献
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An unidirectional 60mm diameter benzophenone single crystal was successfully grown by utilizing a novel crystal growth method at room temperature. <110> oriented single crystal ingots were grown out of xylene as solvent and by fixing a seed at the bottom of the ampoule. The obtained benzophenone ingots with the sizes of 10mm, 25mm and 60mm diameter evident that ease in increasing the diameter of the ingot. The orientation of the ingot and the crystalline quality were justified by X‐ray studies. TG and DTA evaluated the thermal properties of the grown crystal. The optical transmission study and the powder SHG measurement show the suitability of the ingot for nonlinear optical applications. The achieved solute‐crystal conversion efficiency of hundred percent shows vital advantage of this technique for cost effectiveness. The microbial growth as in the case of amino acid based growth solutions can be more effectively controlled in the present method since the freshly prepared growth solution can be constantly made available to the growing crystal. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
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Kouji Maeda Akira Sonoda Hideo Miki Yusuke Asakuma Keisuke Fukui 《Crystal Research and Technology》2004,39(11):1006-1013
Single potassium dihydrogen phosphate (KDP) crystals were grown in a supersaturated solution containing an organic dye (sunset yellow FCF, brilliant blue FCF, and sky blue). The growth rate, morphology, and impurity dye distribution of faces, (100) and (101) in a KDP crystal were measured as dye concentration and the supersatutation of KDP were changed. Complete expressions for the effect of dye on all aspects of the growth of KDP crystals were discussed. The growth rates of (100) and (101) faces were well correlated by the empirical equation, and resulted in good estimation of the morphology. The distribution of dye in a KDP crystal was represented by the distribution model containing the minimum growth rate for coloring. The growth rate equation and distribution equation were expressed by functions of the supersaturation and dye concentration, and they could effectively provide the operational conditions with coloring the KDP crystal. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Kouji Maeda Noriaki Sano Akira Sonoda Keisuke Fukui 《Crystal Research and Technology》2004,39(4):291-296
A new technique to promote crystal growth in aqueous solution using gas plasma is proposed. In this method, short‐lived radical species produced in solution which is contacted with gas corona discharge play a role to increase chemical potential of inorganic solute. In an experimental examination, single crystal of KDP was grown in a supersaturated solution which receives oxygen ions and radicals from adjacent corona discharge in air. KDP crystal has two unique growth faces (100) and (101), and the growth rates of both faces were increased considerably by generating the corona discharge. The both growth rates with and without corona discharge were well converged by one function based on chemical potential supersaturation. This result revealed that the solution in contact with gas corona discharge has a larger capacity of chemical potential than that without the discharge. Short‐lived species induced by gas corona discharge are considered to be anti‐solvents to cause this effect. The crystal growth process proposed here is considered to be an excellent method in terms of low impurity inclusion because such short‐lived species do not remain in the final crystal products and solution. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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〈110〉, 〈010〉 and 〈100〉 oriented uniaxial benzophenone crystals were grown by uniaxially solution‐crystallization method of Sankaranarayanan ‐ Ramasamy (SR). The experimental parameters involved in the present study were investigated in detail and a constant growth rate was achieved by compensating the loss of growth units in the solution. A transparent uniaxial benzophenone crystal having dimension of 500 mm length and 55 mm diameter was grown at room temperature for the first time in the literature. In contrast to the conventional solution growth method, the growth rate along each direction was measured at ease during the respective growth experiment by monitoring the elevation of the solid‐liquid interface and found to be 2, 4 and 6 mm/day along the 〈110〉, 〈010〉 and 〈100〉 directions respectively for a chosen supersaturation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The presented paper (Part I and II) is devoted to the fundamental principles of the kinetics of crystal growth. The number of studies in this field has been increasing and some authors have introduced different terms and definitions. To avoid possible mistakes and confusions, the individual definitions of the rate of crystal growth are specified and their interrelations are discussed in detail. Basic methods for measuring the kinetics of crystal growth are described. The rate of growth of individual crystal faces or the average rate of crystal growth can be determined using the selected experimental method. The presented study demonstrates that the results obtained by either of the two measuring methods (linear rate of growth of crystal faces and average rate of crystal growth) can be interrelated. The established method of calculating linear growth rates of individual crystal faces is based on an analysis of the time dependence of the volume of a growing crystal. The relationship between the linear growth rates of individual crystal faces and the over-all crystal growth rate is presented and a method for assessing the linear growth rates of individual crystal faces from over-all growth rate data, which can be measured readily, is suggested. 相似文献
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A novel crystal growth method has been established for the growth of single crystal with selective orientation at room temperature. Using volatile solvent, the saturated solution containing the material to be crystallized was taken in an ampoule and allowed to crystallize by slow solvent evaporation assisted with a ring heater. The orientation of the growing crystal was imposed by means of a seed fixed at the bottom of the ampoule. By selecting a suitable ring heater voltage and by controlling the ring heater voltage, nucleation and the growth rate of the crystal were controlled more effectively. By employing this novel method, benzophenone single crystal ingots of diameters 10 and 20 mm and length more than 50 mm were successfully grown using xylene as solvent. The ease in scaling up of diameter from 10 to 20 mm shows the vital advantage of this technique. It was possible to achieve solute–crystal conversion efficiency of 100 percent. The grown benzophenone crystal was characterized by FTIR, TG and DTA, powder X-ray diffraction, X-ray rocking curve, optical transmission study and powder SHG measurement. The results show that the crystal quality is at least as good as the quality of the crystal grown by other known methods. Also, microbial growth was naturally avoided in this method, as the fresh solution is constantly made available for the growing crystal. 相似文献